Field of the Invention
This invention relates to an apparatus for assembling semiconductor devices.
Description of the Related Art
FIG. 4 is a block diagram of an example of a conventional assembly apparatus. A stock unit 3 is connected by a transportation unit 2 to a wire bonding unit 1. A lead frame on which a semiconductor chip is mounted is introduced into the wire bonding unit 1 where electrodes of the semiconductor chip and leads of the lead frame are connected to each other by wire bonding. After wire bonding, the lead frame is transported to the stock unit 3 and is stocked therein.
For manufacture of a high-quality semiconductor device, it is necessary to check whether or not the lead frame has been normally wire bonded. Conventionally, for checking, the operator extracts wire bonded i.e., processed, from the transportation unit 2 or the stock unit 3, and carries them to an inspection support separate from the assembly apparatus of FIG. 4. After checking, non-defective lead frames are returned to the stock unit 3.
This process of manually carrying and checking articles entails a risk of the processed articles being contaminated or broken.
In view of this problem, the applicant of the present invention proposed, in Japanese Published Patent Application No. 61-55930, an in-process lead frame transportation unit which is provided in a semiconductor device production line and which includes a lead frame inspection mechanism. FIG. 5 shows a flow diagram of this apparatus. After wire bonding on a lead frame 4 performed by a wire bonding unit 1, the lead frame 4 is transported to an inspection mechanism 7 by an automatic lead frame transportation mechanism 6 to be checked. If the lead frame 4 is determined to be non-defective as a result of checking, it is transported along the line indicated by the arrow A, is temporarily stocked by a non-defective stock mechanism 8, and is thereafter transported to a molding unit 10 or the like for the next step. If the lead frame 4 is defective, it is transported from the inspection mechanism 7 to a defective stock mechanism 9 along the line indicated by the arrow B.
The provision of the inspection mechanism 7 in the production line eliminates the need for the operator to carry worked articles for checking, thereby reducing the risk of contamination or breakage of the processed articles during the inspection process.
However, processed articles are checked ordinarily in a stationary state by means of a microscope or the like, and it is, therefore necessary to stop the flow of the production line for a period of time required to check the articles. If the time required to check one processed article is longer than the time required to process one article in the preceding step or to further process the article in the subsequent step, the overall flow speed of the manufacture line is reduced to enable checking, resulting in a reduction in productivity.